High thermoelectric performance and low thermal conductivity of densified LaOBiSSe

We examined the thermoelectric properties of a densified (hot-pressed) sample of the layered BiCh 2 -based (Ch: S, Se) compound LaOBiSSe. The values obtained for the power factor ( S 2 /ρ) when measured perpendicular to the pressing direction ( P ⊥ ) were higher than those when measured parallel to the pressing direction ( P ∥ ). The thermal conductivity (κ) of the samples was also sensitive to the crystal orientation. The values of κ measured along P ∥ were lower than those measured along P ⊥ . The highest dimensionless figure-of-merit ( ZT ∼ 0.36) was obtained at around 650 K in both directions, i.e., P ⊥ and P ∥ .